Electronic equipment such as a hard disk drive is provided with a spindle motor that rotates a disk. The spindle motor includes a stationary section that is fixed to a housing of the electronic equipment and a rotating section that rotates while supporting the disk.
The stationary section and the rotating section of the spindle motor are connected to each other through a dynamic pressure bearing unit. A dynamic pressure bearing unit in the related art includes, for example, a shaft member, a sleeve, and a housing receiving the sleeve. The dynamic pressure bearing unit in the related art and a spindle motor including the dynamic pressure bearing unit are disclosed in, for example, JP-A-2004-176816.
In JP-A-2004-176816, a circumferential groove is formed on an upper end face of a bearing sleeve. When the circumferential groove is to be formed on the upper end face of the bearing sleeve by, for example, press forming, there is a problem in that an inner peripheral surface of the bearing sleeve protrudes inwardly in a radial direction during the press forming. In this case, a gap, which is formed between an outer peripheral surface of the shaft member and the inner peripheral surface of the bearing sleeve, becomes non-uniform. For this reason, the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing sleeve come into contact with each other during the drive of the spindle motor.